Body-warming and body-cooling devices are known for application to a portion of a body, such as hands, head, ears and back to provide Warmth or cooling for comfort and for therapeutic purposes. For example, heating pads, ice packs and cold compresses are used for such purposes. Some hot and cold packs include a liquid solution or gel material sealed within a flexible container for storing thermal energy. Such containers may burst in response to overheating. In the event the container should rupture, the hot liquid or gel material will leak and may cause burn injury to the user. Moreover, in the event such a liquid or gel material should be used in a cold pack, there is a risk that the container may rupture upon being frozen, thereby permitting the liquid or gel material to leak upon thawing.